I am not exactly sure what you imagine, but I (in Germany) have two 3 phase outlets (3x 16A @230V) in my flat and this is very common here. We use it for cook tops and ovens in the kitchen typically, and it makes the difference between 15 mins for boiling water (old single phase cook top) and (on my induction cook top) 1 min.

Edit: and as an aside, why we probably don't do that everywhere: it makes for bigger plugs, and keeping safety standards can be a bit more expensive and space intensive with the potential 400V between phases.